1. Field of the Invention
The present invention relates to a drive axle suspension system for heavy vehicles which has been optimized for reduced weight, reduced part count and increased durability.
2. Technical Background
Various suspension systems utilizing air springs have been developed for semi-tractor trailers and other heavy vehicles. These systems are typically designed to control the position of the chassis relative to an associated axle and to cushion any movement of the axle with respect to the chassis frame. Although these systems provide excellent chassis control over a wide range of loading conditions, conventional air spring systems typically do not offer acceptable resistance to vehicle roll, as is often experienced when the vehicle turns, nor do they offer acceptable resistance to lateral shifting of the vehicle.
While specialized components have been added to air spring systems to reduce roll and lateral shift, many of these components add significant weight and cost and maintenance to the associated suspension system without greatly reducing the roll and lateral shift. Specifically, these designs typically incorporate single-piece trailing arms that require materials meeting torsional and sheer strength requirements, but that also may be tapped and threaded as required. Further, many of these components include complicated designs that are not only expensive to manufacture, but are also difficult to install or replace should damage to the component or related equipment occur. One particular assembly is adapted to stabilize the related suspension system by securing a torsional beam between a pair of trailing arms by bolts that extend through the torsional beam and into threaded apertures located in the ends of the beams. This particular assembly requires large securing bolts adapted to withstand significant torsional and sheering forces, and further requires the replacement or retapping of a trailing arm should the threads within the bolt receiving aperture become damaged or worn as well as maintenance burden.
There is a need for a lightweight and inexpensive air spring suspension system that resists roll and lateral shift, will not significantly impact the ride-cushioning characteristics of such suspension system, provides a relative increase of structural integrity, and that can further be maintained and repaired quickly and cost-effectively.